Antenna for wireless charging systems

ABSTRACT

A metamaterial system of a wireless transmission apparatus comprises a metamaterial layer. The metamaterial layer comprises an array of unit cells wherein each of the unit cell comprises a surface having a metal patch with an aperture. The aperture is defined such that a periphery of the aperture is within a periphery of the surface by a spacing distance and an element is disposed within the aperture. The metamaterial system further comprises at least one input RF port placed on a backing layer disposed below the metamaterial layer such that there is no short-circuit between the conductive backing layer and the metamaterial layer; and at least one set of vias connecting the array of unit cells with the at least one input RF port.

TECHNICAL FIELD

This application generally relates to wireless charging systems, and inparticular, to metamaterial unit cells configured to radiate wirelesspower signals to power electronic devices.

BACKGROUND

Wireless charging systems have been made to wirelessly transmit energyto electronic devices, where a receiver device can consume thetransmission and convert it to electrical energy. Wireless chargingsystems are further capable of transmitting the energy at a meaningfuldistance. The wireless charging systems make use of an array of antennasto provide spatial diversity, focus the wireless transmission waves at atarget location, direction-finding, and increased capacity.

Numerous attempts have been made in new generation wireless chargingsystems to incorporate techniques to achieve high performance goals. Theperformance achievable by the new generation wireless charging systemsis still limited due to a number of practical design factors includingthe design of the antenna array. The accommodation of the multipleantennas with large spacing in modern wireless charging systems hasbecome difficult due to stringent space constraints in the newgeneration wireless charging systems. Typically, the dimensions of anantenna are determined by the frequency at which the antenna is designedto function. The ideal antenna is some multiple of the electromagneticwavelength such that the antenna can support a standing wave. Theantennas usually do not satisfy this constraint because antennadesigners either require the antenna to be smaller than a particularwavelength, or the antenna is simply not allotted the required volume ina particular design in the new generation wireless charging systems.When the antenna is not at its ideal dimensions, the antenna losesefficiency. The antenna is also often used to capture informationencoded on an electromagnetic wave. However, if the antenna is smallerthan an incoming electromagnetic wavelength, the information is capturedinefficiently and considerable power is lost. In order to meet suchdemanding design criteria, antenna designers have been constantly drivento seek better materials on which to build antenna systems for the newgeneration wireless charging systems.

In recent times, antenna designers have used metamaterials.Metamaterials are a broad class of synthetic materials that have beenengineered to yield permittivity and permeability values or otherphysical characteristics, not found in natural materials, aligned withthe antenna system requirements. It has been theorized that by embeddingspecific structures in some host media usually a dielectric substrate,the resulting material can be tailored to exhibit desirablecharacteristics. These promise to miniaturize antennas by a significantfactor while operating at acceptable efficiencies.

In the context of antenna systems for the new generation wirelesscharging systems, metamaterials have been used as substrates orsuperstrates on existing antennas to enhance their properties. Incurrent art, the metamaterial is usually integrated behind the antenna,either monolithically on the same PCB as the printed antenna, or as aseparate structure in close proximity to the antenna. Alternatively, themetamaterial can be integrated on an already directive antenna tofurther enhance its directivity and gain. The benefit of integrating themetamaterial to the antenna enhances various properties of the antennassuch as it creates one or more directive beams. It has been noted thatcertain metamaterials can transform an omnidirectional antenna into avery directive one while maintaining very thin profiles. However, due tothe presence of a layer of antennas along with metamaterials layer, anoptimal size and performance is not achieved by the metamaterial antennasystems for the new generation wireless charging systems. Accordingly,there is a need in the art for metamaterial antenna systems that providean optimal size and performance for modern wireless charging systemshaving stringent space constraints.

SUMMARY

Metamaterials are artificial composites that achieve materialperformance beyond the limitation of uniform materials and exhibitproperties not found in naturally-formed substances. Such artificiallystructured materials are typically constructed by patterning orarranging a material or materials to expand the range of electromagneticproperties of the material. When an electromagnetic wave enters amaterial, the electric and magnetic fields of the wave interact withelectrons and other charges of the atoms and molecules of the material.These interactions alter the motion of the wave changing theelectromagnetic wave propagation properties in the material, e.g.,velocity, wavelength, direction, impedance, index of refraction, and thelike. Similarly, in a metamaterial, the electromagnetic wave interactswith appropriately designed artificial unit cells that macroscopicallyaffect these characteristics. In an embodiment, the metamaterial maycomprise an array of unit cells formed on or in a dielectric substrateand are configured to radiate wireless power signals to power electronicdevices.

In one embodiment, a wireless transmission apparatus comprises ametamaterial unit cell. The metamaterial unit cell may include a surfacehaving a metal patch with an aperture. The aperture is defined such thata periphery of the aperture is within a periphery of the surface by aspacing distance. An antenna element is disposed within the aperture.

In another embodiment, a method of forming a unit cell is provided. Themethod comprises forming a metamaterial layer using metamaterialsubstrate. A surface on the metamaterial layer may be created, and ametal patch with an aperture in the surface of the metamaterial layermay be created. An antenna element may be disposed in the aperture toform the unit cell.

In another embodiment, a metamaterial system (or a metamaterial board)of a wireless transmission apparatus comprises a metamaterial layer. Themetamaterial layer may include an array of metamaterial unit cells,where each of the metamaterial unit cells may include a surface havingan aperture. The aperture is defined such that a periphery of theaperture is within a periphery of the surface by a spacing distance. Anantenna element is disposed within the aperture. The metamaterial systemmay further include at least one input RF port disposed on a backinglayer that is positioned below the metamaterial layer such that there isno short-circuit between the conductive backing layer and themetamaterial layer. At least one set of vias may connect the array ofmetamaterial unit cells with the input RF port(s).

In another embodiment, a method of forming a metamaterial system isprovided. The method comprises forming a backing layer. A metamateriallayer may be formed from a metamaterial substrate. The metamateriallayer may be formed above the backing layer. Multiple partitions may becreated in the metamaterial layer, where each of the partitions define aportion of a unit cell of a plurality of unit cells. The method furtherincludes creating an aperture in each of the partitions, where theaperture is defined such that a periphery of the aperture is within aperiphery of a partition in which the aperture is created by a spacingdistance. An element may be disposed in the aperture in each of theplurality of partitions. At least one input RF port may be formed on thebacking layer such that there is no short-circuit between the backinglayer and the metamaterial layer. The unit cells may be connected withthe input RF port(s) by at least one set of vias.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

The accompanying drawings constitute a part of this specification andillustrate an embodiment of the invention and together with thespecification, explain the invention.

FIG. 1A illustrates an isometric view of a structure of a metamaterialboard having a contactless capacitive coupling mechanism, according toan exemplary embodiment.

FIG. 1B illustrates a graph depicting a return loss of a metamaterialboard having a contactless capacitive coupling mechanism of FIG. 1A,according to an exemplary embodiment.

FIG. 1C illustrates an isometric view of a radiation gain pattern of ametamaterial board having a contactless capacitive coupling mechanism ofFIG. 1A, according to an exemplary embodiment.

FIG. 1D illustrates a profile view of a radiation gain pattern in linearscale of a metamaterial board having a contactless capacitive couplingmechanism of FIG. 1A, according to an exemplary embodiment.

FIG. 1E illustrates a polar plot of a radiation gain pattern on aprincipal Y-Z plane of a metamaterial board having a contactlesscapacitive coupling mechanism of FIG. 1C, according to an exemplaryembodiment.

FIG. 1F illustrates a magnitude of electric current surface densitydistribution on metamaterial cells layer of a metamaterial board havinga contactless capacitive coupling mechanism of FIG. 1A at operationalfrequencies, according to an exemplary embodiment.

FIG. 1G illustrates a magnitude of electric current surface densitydistribution on backing conductor layer of a metamaterial board having acontactless capacitive coupling mechanism of FIG. 1A at operationalfrequencies, according to an exemplary embodiment.

FIG. 2 illustrates an isometric view of a structure of a metamaterialboard having a co-planar coupling mechanism, according to an exemplaryembodiment.

FIG. 3A illustrates an isometric view of a structure of a metamaterialboard having a direct feeding excitation mechanism, according to anexemplary embodiment.

FIG. 3B illustrates a graph depicting a return loss of a metamaterialboard having a direct feeding excitation mechanism of FIG. 3A, accordingto an exemplary embodiment.

FIG. 3C illustrates an isometric view of a radiation gain pattern of ametamaterial board having a direct feeding excitation mechanism of FIG.3A, according to an exemplary embodiment.

FIG. 3D illustrates a magnitude of electric current surface densitydistribution on metamaterial cells layer of a metamaterial board havinga direct feeding excitation mechanism of FIG. 3A at operationalfrequencies, according to an exemplary embodiment.

FIG. 3E illustrates an isometric view of a structure of a metamaterialboard having a direct feeding excitation mechanism, according to anexemplary embodiment.

FIG. 3F illustrates a graph depicting a return loss of a metamaterialboard having a direct feeding excitation mechanism of FIG. 3E, accordingto an exemplary embodiment.

FIG. 4 illustrates an enlarged sectional view of a structure of ametamaterial board having a contactless capacitive coupling mechanism, aco-planar coupling mechanism, and a direct feeding excitation mechanism,according to an exemplary embodiment.

FIG. 5A illustrates an isometric view of a structure of a metamaterialboard having a direct feeding excitation mechanism, according to anexemplary embodiment.

FIG. 5B illustrates a graph depicting a return loss of a metamaterialboard having a direct feeding excitation mechanism of FIG. 5A, accordingto an exemplary embodiment.

FIG. 5C illustrates an isometric view of a radiation gain pattern of ametamaterial board having a direct feeding excitation mechanism of FIG.5A, according to an exemplary embodiment.

FIG. 5D illustrates an isometric view of a structure of a metamaterialboard having a direct feeding excitation mechanism, according to anexemplary embodiment.

FIG. 5E illustrates a graph depicting a return loss of a metamaterialboard having a direct feeding excitation mechanism of FIG. 5D, accordingto an exemplary embodiment.

FIG. 5F illustrates an isometric view of a radiation gain pattern of ametamaterial board having a direct feeding excitation mechanism of FIG.5D, according to an exemplary embodiment.

FIG. 6A illustrates a configuration of metamaterial unit cells for useas wearable antennas, according to an exemplary embodiment.

FIG. 6B illustrates an enlarged sectional view of a metamaterial unitcells as wearable antennas, according to an exemplary embodiment.

FIG. 6C illustrates a graph depicting a return loss metamaterial unitcells as wearable antennas of FIG. 6A, according to an exemplaryembodiment.

FIG. 6D illustrates an isometric view of a radiation gain pattern ofmetamaterial unit cells as wearable antennas of FIG. 6A, according to anexemplary embodiment.

FIG. 7A illustrates a structure of metamaterial unit cells configured aswearable antennas, according to an exemplary embodiment.

FIG. 7B illustrates an enlarged sectional view of a structure ofmetamaterial unit cells configured as wearable antennas, according to anexemplary embodiment.

FIG. 8A illustrates an isometric view of a structure of a metamaterialboard configured as an antenna array, according to an exemplaryembodiment.

FIG. 8B illustrates a graph depicting a return loss of a metamaterialboard configured as an antenna array of FIG. 8A, according to anexemplary embodiment.

FIG. 8C illustrates an isometric view of a radiation gain pattern of ametamaterial board configured as an antenna array of FIG. 8A, accordingto an exemplary embodiment.

FIG. 9A illustrates an isometric view of a metamaterial board includingtwo orthogonal sub-arrays, according to an exemplary embodiment.

FIG. 9B illustrates a planar view of a radiation gain pattern of ametamaterial board including two orthogonal sub-arrays of FIG. 9A,according to an exemplary embodiment.

FIG. 9C illustrates a planar view of a radiation gain pattern of ametamaterial board including two orthogonal sub-arrays of FIG. 9A,according to an exemplary embodiment.

FIG. 9D illustrates a planar view of a radiation gain pattern of ametamaterial board including two orthogonal sub-arrays of FIG. 9A,according to an exemplary embodiment.

FIG. 9E illustrates an isometric view of a radiation gain pattern of ametamaterial board including two orthogonal sub-arrays of FIG. 9A,according to an exemplary embodiment.

FIG. 10 illustrates a method of forming a metamaterial board, accordingto an exemplary embodiment.

DETAILED DESCRIPTION

The present disclosure is herein described in detail with reference toembodiments illustrated in the drawings, which form a part here. Otherembodiments may be used and/or other changes may be made withoutdeparting from the spirit or scope of the present disclosure. Theillustrative embodiments described in the detailed description are notmeant to be limiting of the subject matter presented here.

In an embodiment, a response of a structure in any material toelectromagnetic waves may be described by overall parameters, such aspermittivity and permeability of the material, where the dimensions ofthe structure are far smaller than the wavelength of the electromagneticwave. The permittivity and the permeability at each point of thematerial may be the same or different, so that the overall permittivityand the overall permeability of the material are distributed regularlyto some extent. The regularly distributed permeability and permittivitycan cause the material to exhibit a macroscopic response to theelectromagnetic wave, for example, converging the electromagnetic wave,diverging the electromagnetic wave, and the like. Such a material withregularly distributed permeability and permittivity is calledmetamaterial. In other words, metamaterials are a broad class ofsynthetic materials that are engineered to yield permittivity andpermeability characteristics compliant with the system requirements. Byembedding specific structures, usually periodic structures, in some hostmedia, usually a dielectric substrate, the resulting material istailored to exhibit desirable characteristics. These metamaterialsenable miniaturizing antennas by a significant factor while operating atacceptable efficiencies. The metamaterials may also convertomnidirectionally radiating antennas into directively radiatingantennas.

In an embodiment, metamaterials of the present disclosure do not need anadditional layer of antennas for the metamaterials to radiate. Themetamaterials radiate on their own, and at the same time, themetamaterials maintain the properties of a traditional antenna-typemetamaterials. In other words, the metamaterials act as very thinreflectors, and at the same time, the metamaterials do not need antennasfor radiating as the metamaterials radiate themselves.

In an embodiment, the metamaterials of the present disclosure work likeartificial magnetic conductors. The metamaterials are configured as verythin reflectors, and therefore the metamaterials are easy to integratein very thin profiles of products, such as wearable bracelets.

In an embodiment, there is provided a metamaterial system (also referredas metamaterial board) that comprises at least two metal layers and athin substrate. The structure of the metamaterial system of the presentdisclosure provides for no antenna placement layers in relation to priorart implementations that require at least three metallization layersbecause of the additional antenna layer for the placement of antennas.Further, the metamaterial system of the present disclosure is muchthinner in size than the prior art implementations as absence ofadditional antenna layers, often at prescribed non-negligible distancesfrom the ordinary metamaterials, reduce significantly the overall systemthickness that incorporates the metamaterial system. Therefore, themetamaterial system of the present disclosure due to absence of anylayer of antennas results in very thin profiles, and is appropriate fordense integration at reduced cost.

In an embodiment, there is provided a metamaterial system composed ofseveral sub-wavelength-sized “artificial atoms” or radiativemetamaterial unit cells. The metamaterial system operates byelectromagnetically exciting all of the radiative metamaterial unitcells simultaneously. The metamaterial system also have many degrees offreedom that may translate into beam-forming possibilities that areunavailable with a conventional single antenna. In one example, someregions of the metamaterial system contain the radiative metamaterialunit cells that have different design and radiative properties thanother regions of the same metamaterial system. The radiativemetamaterial unit cells facilitate creation of beam-forming and/or beamsteering without introduction of any phase-shifting networks.

In an embodiment, there is provided a metamaterial system composed ofseveral radiative metamaterial unit cells. The metamaterial system mayobtain linear, circular or elliptical polarization by appropriatelydesigning the radiative metamaterial unit cells. The linear, circular orelliptical polarization properties may be obtained by the metamaterialsystem that is composed of regions of the radiative metamaterial unitcells, where each of the radiative metamaterial unit cell has adifferent design with respect to other metamaterial unit cells. In otherwords, since the radiative metamaterial unit cells radiate on their own,designing the radiative metamaterial unit cells appropriately may obtainvarious different functionalities, such as linear, circular, circular,or elliptical polarization.

In an embodiment, there is provided a metamaterial system composed ofradiative metamaterial unit cells. The radiative metamaterial unit cellsmay be electrically interconnected by switches realized by integrateddiodes, RF microelectromechanical (MEM) devices, or other means, to formlarger radiative domains or different metamaterial “super-cells” thatscan selected frequencies of operation over which the electromagneticradiation is desired.

In an embodiment, there is provided a metamaterial system composed of anarray of unit cells. The array of unit cells radiate on their own andhave engineered metamaterials. In one implementation, an array ofswitches may be constructed by connecting adjacent unit cells of thearray of unit cells. In other words, the metamaterial system is composedof a lattice of unit cells, and a lattice of switches can bemanufactured by connecting adjacent unit cells through diodes. Thelattice of switches may be superimposed on the lattice of the unitcells, and because the switches connect adjacent unit cellselectronically, there may be a configuration where the metamaterial hastwo types of unit cells, one type of unit cells that are not connected,and the other type of unit cells where a pair of unit cells areconnected. In the latter case, the electrical size may be variableaccording to whether the switches are open or closed. In thisconfiguration, the frequency may be varied according to whether or notthe switches to connect adjacent unit cells. This is also called smartradiative metamaterials, where the frequency tuning is arranged throughthe connectivity of the switches.

In an embodiment, there is provided a metamaterial system composed ofradiative metamaterial unit cells. The metamaterial unit cells areextremely small in size due to which resulting metamaterial antennasoccupy small form factors and are ideally suited to follow the curvedshapes of wearable and other conformal applications. In other words, theform factors are proportional to the size of the metamaterial unitcells. Due to smaller size, the metamaterial unit cells may be placed onflexible/wearable substrates to realize wearable antennas or antennas incurved geometries.

In an embodiment, there is provided a metamaterial system that iscomposed of several radiative metamaterial unit cells. The metamaterialunit cells are extremely small in size due to which there are smallerform factors, and because of the small form factors, the radiativemetamaterial unit cells may be placed in closely spaced orthogonalorientations, and thus forming dual linearly-polarized antenna systemsthat are able to transmit or receive electromagnetic wavessimultaneously in orthogonal linear polarizations. The simultaneoustransmission and receiving of the electromagnetic waves in orthogonallinear polarizations can be realized within very small areas, such ascurved wearable platforms (e.g., wearable bracelets).

In an embodiment, there is provided a metamaterial system that iscomposed of radiative metamaterial unit cells. The radiativemetamaterial unit cells in a receiving mode operate as uniform materialsthat absorb electromagnetic radiation with high absorption efficiency.The radiative metamaterial unit cells may further operate over a widerange of frequencies, including a microwave spectrum. The radiativemetamaterial unit cells have a very high absorption efficiency (90% orhigher). In another embodiment, the radiative metamaterial unit cellsmay be tapped by inserting localized radio frequency (RF) ports toarbitrary metamaterial unit cells. This power is then directedspecifically to these RF ports. Thus, the radiative metamaterial unitcells work as a dense antenna array with many RF ports that receive theabsorbed energy. Such metamaterial system is ideal for very smallreceivers, where the received power may be distributed to multiplechannels simultaneously. A high density of the RF ports may be achieved,with each such RF port tapping adjacent radiative metamaterial unitcells. An even higher density of the RF ports may be achieved, with someRF ports tapping the same radiative metamaterial unit cell, providedadditional decoupling techniques are employed. In addition, thesemultiple densely placed RF ports can accept phase control, resulting inelectronically modulated RF patterns.

Reference will now be made to the illustrative embodiments illustratedin the drawings, and specific language will be used here to describe thesame. It will nevertheless be understood that no limitation of the scopeof the invention is thereby intended. Alterations and furthermodifications of the inventive features illustrated herein, andadditional applications of the principles of the inventions asillustrated herein, which would occur to one skilled in the relevant artand having possession of this disclosure, are to be considered withinthe scope of the invention.

FIG. 1A illustrates an isometric view of a structure of a metamaterialboard 100 having a contactless capacitive coupling mechanism, accordingto an exemplary embodiment. The metamaterial board 100 illustrated hereis realized in standard Printed Circuit Board (PCB) technology utilizingthree metal layers. Three metal layers may include a conductive backinglayer 102, a metamaterial layer 104, and a coupling layer 106. Also, adielectric layer 108 is disposed between the conductive backing layer102 and the metamaterial layer 104.

In the metamaterial board 100 fabrication, the conductive backing layer102 is placed at the bottom of the structure of the metamaterial board100. The metamaterial layer 104 may be deposited above the conductivebacking layer 102, and then may be etched to create an array ofmetamaterial unit cells 104 a. Hereinafter, the term “unit cell” and“metamaterial unit cell” may be interchangeably used. In an embodiment,a distance between the conductive backing layer 102, and themetamaterial layer 104 is such that there is no short-circuit betweenthe conductive backing layer 102, and the metamaterial layer 104 inorder to make the metamaterial unit cells 104 a radiate. Below themetamaterial layer 104 and above the conductive backing layer 102 may bedeposited a layer of dielectric 108 or insulating material, often asilicon dioxide.

The metamaterial layer 104 comprises the array of unit cells 104 a. Inthe illustrative figure, the metamaterial layer 104 of the metamaterialboard 100 comprises sixteen radiative metamaterial unit cells 104 a in afour-by-four (4×4) arrangement. Each of the metamaterial unit cell 104 amay include a surface. In one embodiment, the surface may be asubstantially flat surface. In another embodiment, the surface may notbe a flat surface or a substantially flat surface. The substantiallyflat surface of each of the array of metamaterial unit cells 104 a maybe a square surface containing a square metal patch 104 b with anaperture 104 c inscribed within it. The square metal patch 104 b doesnot completely fill the metamaterial unit cell surface, but is slightlysmaller than the metamaterial unit cell. The aperture 104 c is definedsuch that a periphery of the aperture 104 c is within a periphery of thesquare metal patch 104 b by a spacing distance. In one example, theaperture 104 c may be a circular aperture. An element 104 d may bedisposed within the aperture 104 c to form a circular slot. In anotherexample, the aperture may be a narrow shaped circular slot formed by thecircular shape aperture 104 c and the element 104 d disposed within it.In the illustrated embodiment, since the aperture 104 c is circular inshape, the element 104 d is a circular metal disk that is disposedwithin aperture 104 c to form the circular slot. It will be appreciatedby a person having ordinary skill in the art that the shape of theaperture 104 c is not limited to circular shape, and the aperture 104 cmay be of any other suitable shape without moving out from the scope ofthe disclosed embodiments. Also, the array composed of metamaterial unitcells 104 a contains square metal patches that do not touch each other,but are separated by narrow straight slots, since the metamaterial unitcell surface is slightly larger than that of the square metal patch 104b inscribed therein. Further, there is a thin slot separating thecircular element 104 d from the periphery of the square metal patch 104b. In an embodiment, one subset of the array of the metamaterial unitcells 104 a may be of one shape and size, and another subset of thearray of the metamaterial unit cells 104 a may be of another shape andsize.

In one embodiment, one metamaterial unit cell 104 a on its own does notradiate efficiently and also does not match the required impedancevalue. In other words, one metamaterial unit cell 104 a does not haveproperties for a standard antenna. The array or the collection of themetamaterial unit cells 104 a work together as an antenna. Therefore,the metamaterial board 100 may include 16 unit cells 104 a. However, itis to be noted that the metamaterial board 100 may comprise any numberof unit cells 104 a in other embodiments without moving out from thescope of the disclosed embodiments.

In another embodiment, the metamaterial layer 104 may comprise the arrayof unit cells 104 a formed on or in a dielectric substrate. In someembodiments, the metamaterial layer 104 may comprise a stack of 2Darrays of unit cells 104 a, where each 2D array of unit cells 104 a isformed on or in a respective dielectric substrate. In thisimplementation, magnetic permeability enhanced metamaterials areconstructed by stacking up the unit cells 104 a that can store magneticenergy by virtue of their structure. The unit cell 104 a in embodimentsof the present disclosure is composed of the circular element 104 d andthe square metal patch 104 b, where the circular element 104 d may beembedded in a dielectric material. The magnetic energy storage iscreated in the unit cell 104 a when a magnetic field passes normally tothe plane of the circular element 104 d and inducing a current in theloop.

The dielectric layer 108 may be masked and etched to open narrow profileopenings known as vias 110. Each of the vias 110 respectively extend asan opening through the dielectric layer 108 to a portion of theuppermost coupling layer 106. In one embodiment, the vias 110 may bepresent to provide electrical paths between different metal layers ofthe metamaterial board 100. The vias 110 may run from a surface of themetamaterial board 100 through each of the layers of the metamaterialboard 100. In another embodiment, the vias 110 may run from one layer ofthe metamaterial board 100 or a surface of the metamaterial board 100and through other layers of the metamaterial board 100 but stop short ofrunning through one of the layers. At a first surface of themetamaterial board 100, the vias 110 may terminate on bond pads thatcouple to the integrated circuit. An opposite surface of themetamaterial board 100 is to be coupled to a PCB. As discussed above,certain vias 110 may go entirely through entire core of the metamaterialboard 100. Other vias 110 may be isolated vias 110, which are presentthrough only a portion of the metamaterial board 100. The particularlayering and the vias 110 pattern configuration utilized is a matter ofdesign choice involving several factors related to the purposes to beserved by the particular metamaterial board 100. In order to form themetamaterial board 100 with the vias 110 as described above, once apattern of the vias 110 to traverse the layers is determined, theseparticular vias 110 may be machine drilled, punched, or etched throughthe layers. Alternative techniques for providing electrical pathsbetween the layers may be utilized.

In the illustrated figure, the vias 110 extend from the uppermostcoupling layer 106 to input RF ports 112. The input RF ports 112 may belocated on or behind the conductive backing layer 102. The input RFports 112 may include a housing having any arbitrary shape, andmanufactured from plastic, metal, or any other convenient material. Theinput RF ports 112 may be configured such that two or more submodulesmay be removably located within or attached to housing. That is, thesubmodules are removably coupled electrically, and may be removablyinserted within housing. In an alternate embodiment, the submodules areremovably attached to the exterior of housing. The input RF ports 112are not limited to two submodules, and may be configured to accommodate3, 4, or even more such submodules. The submodules may include a varietyof electrical components that communicate via RF energy. In general, thesubmodules are capable of fulfilling many of the functions of thecomponents.

In another embodiment, another layer of metal may be deposited over thedielectric layer 108. The deposited metal fills the vias 110, formingmetallic contact structures engaging the exposed underlying metal at thebottom of the vias and making points of contact through layer betweenthe conductive backing layer 102 and the uppermost coupling layer 106.The geometries of the vias 110 and the contact structures that now fillthe vias 110 are usually circular, although the vias 110 may also formother shapes such as a trench shape. The vias 110 have been positionedso that the metallic structures which fill the vias 110 provide contactsbetween two separated metal layers of the metamaterial board 100.

In an embodiment, the contactless capacitive coupling excitationmechanism is used to excite the structure of the metamaterial board 100.Some of the components utilized for the contactless capacitive couplingexcitation mechanism are provided above the metamaterial layer 104 atthe center of the metamaterial board 100 to excite the structure of themetamaterial board 100. The components at least include a plurality ofpads 114 on the coupling layer 106. The plurality of pads 114 are usedto excite the metamaterial unit cells of the metamaterial board 100. Theplurality of pads 114 are connected through the vias 110 that traversethough the metamaterial layer 104 of the metamaterial board 100 up tothe conductive backing layer 106 of the metamaterial board 100. In thepresent embodiment, the excitation of the metamaterial unit cells of themetamaterial layer 104 is achieved without direct contact by acapacitive structure (of small size) that couples RF power from theinput RF port 112 to the metamaterial layer 104. Also, the plurality ofpads 114 (of square shape) placed above the metamaterial layer 104, andgoing through the vias 110 behind the structure of the metamaterialboard 100 excite the metamaterial unit cells as a capacitor, andtherefore such a coupling is called the capacitive coupling. Thecontactless capacitive coupling excitation mechanism enables three metallayers of the metamaterial board 100. In alternate embodiments describedfurther herein, the excitation of the metamaterial board 100 may utilizefewer than or more than three metal layers.

In an embodiment, the two vias 110 connect to the RF port 112, andtherefore have a positive polarity and a negative polarity. One of thevias 110 at a negative potential is configured to excite half of themetamaterial unit cells 104 a, and the other of two vias 110 at apositive potential is configured to excite remaining half of themetamaterial unit cells 104 a. In the contactless capacitive couplingmechanism, a single via 110 with the corresponding pad 114 excites theadjacent metamaterial unit cells 104 a of the metamaterial board 100simultaneously because of a finite size of the corresponding pad 114 andsince the corresponding pad 114 couples to both of the adjacentmetamaterial unit cells 104 a equally.

In illustrative embodiment, the metamaterial unit cell 104 a is a squaresurface surrounding the square metal 104 b comprising the aperture, andthe metallic element 104 d disposed within the aperture 104 c. Themetallic element 104 d is a circular metal disk that has a smallerdiameter than the aperture 104 c. The size of the aperture 104 c isinversely proportional to a frequency of operation. If the size of theaperture 104 c is reduced, the size of the metallic element 104 ddisposed within the aperture 104 c is also reduced, and then thefrequency of the operation moves up. If the size of the aperture 104 cis increased, the size of the metallic element 104 d disposed within theaperture 104 c also becomes larger, and then the frequency at which themetamaterial unit cell 104 a operates goes down. The aperture 104 c maybe of circular shape. In an alternate embodiment, the aperture 104 c maybe of an elliptical shape. Alternate shapes may be utilized.

In illustrative embodiment, the radiating structure of the metamaterialboard 100 is linearly polarized, and has a transmit mode and a receivemode. In the transmit mode/configuration, the radiating structure of themetamaterial board 100 emits radiation where the electric field has aspecific direction along a single line. In the receivemode/configuration, the radiating structure of the metamaterial board100 receives the radiation.

FIG. 1B illustrates a graph depicting the return loss of a metamaterialboard 100 having a contactless capacitive coupling mechanism of FIG. 1A,according to an exemplary embodiment. The return loss (reflected power)of the metamaterial board 100 having the contactless capacitive couplingis measured in dB. The metamaterial board 100 having the contactlesscapacitive coupling mechanism resonates at a center frequency of 6 GHz.The impedance matching here to a 50 Ohm RF port is at below −25 dB. Theimpedance matching represents matching of the metamaterial board 100having the contactless capacitive coupling mechanism to a standard RFport, which is typically 50 ohm. The impedance matching bandwidth at the−10 dB level is 350 MHz, or 6% with respect to a center frequency of themetamaterial board 100. The impedance matching defines the operationfrequency band of the structure of the metamaterial board 100 having thecontactless capacitive coupling mechanism. In one embodiment, thedimensions of the metamaterial board 100 having the contactlesscapacitive coupling mechanism may be chosen so that the metamaterialboard 100 having the contactless capacitive coupling mechanism tune to astandard operation frequency around 500 GHz. In another embodiment,impedance matching to other RF port values is possible withmodifications of the presented shapes without moving out from the scopethe disclosed embodiments.

FIG. 1C illustrates an isometric view of a radiation gain pattern, indB, of a metamaterial board 100 having a contactless capacitive couplingmechanism of FIG. 1A, according to an exemplary embodiment. As shown,the metamaterial board 100 having the contactless capacitive couplingmechanism has a single directive electromagnetic beam of energy that isradiating upward/forward along the z-axis. The single directiveelectromagnetic beam is generated by excitation of entire sixteenmetamaterial unit cells 104 a of the metamaterial board 100.

FIG. 1D illustrates a polar plot of a radiation gain pattern in linearscale of a metamaterial board 100 having a contactless capacitivecoupling of FIG. 1A, according to an exemplary embodiment. As shown, themetamaterial board 100 having the contactless capacitive couplingmechanism has a single directive electromagnetic beam of energy that isdirected broadside, with negligible radiation behind the metamaterialboard 100. The single directive electromagnetic beam is generated byexcitation of entire sixteen metamaterial unit cells 104 a of themetamaterial board 100.

FIG. 1E illustrates a polar plot of a radiation gain pattern, in dB, ona principal Y-Z plane of a metamaterial board 100 having a contactlesscapacitive coupling of FIG. 1C, according to an exemplary embodiment.The electromagnetic radiation emitted from the metamaterial board 100having the contactless capacitive coupling mechanism is linearlypolarized, with a cross-polarization level at about 40 dB below aco-polarized radiation. In an embodiment, the metamaterial board 100back-side radiation is suppressed and a front-to-back gain ratio isabout 17 dB.

FIG. 1F illustrates a magnitude of electric current surface densitydistribution on metamaterial unit cells layer 104 of a metamaterialboard 100 having a contactless capacitive coupling mechanism of FIG. 1Aat operational frequencies, according to an exemplary embodiment. Themagnitude of the electric current surface density distributed on theradiative metamaterial unit cells 104 a of the metamaterial board 100having the contactless capacitive coupling mechanism, at the operatingfrequency band, where the metamaterial unit cells 104 a of themetamaterial board 100 radiates is shown. In one embodiment, a pluralityof metamaterial unit cells 104 a of the metamaterial board 100 areexcited from the contactless capacitive coupling mechanism andsubsequently strong electric currents develop both on square patch edgesand on circular slot edges of each of the metamaterial unit cells 104 aof the metamaterial board 100. This results in the plurality ofmetamaterial unit cells 104 a of the metamaterial board 100 contributingto the electromagnetic radiation simultaneously, thereby leading to ahigh radiative gain of the metamaterial board 100. In anotherembodiment, all the metamaterial unit cells 104 a of the metamaterialboard 100 are excited from the contactless capacitive coupling mechanismdue to strong electric currents that develop both on the square patchedges and on the circular slot edges of each of the metamaterial unitcells 104 a of the metamaterial board 100. In this embodiment, all themetamaterial unit cells 104 a of the metamaterial board 100 contributingto the electromagnetic radiation simultaneously, thereby leading to ahigh radiative gain of the metamaterial board 100. It is contemplatedthat an alternate embodiment may actively or passively engage aplurality, but not all, metamaterial unit cells 104 a to contribute tothe electromagnetic radiation. In an embodiment, although the excitationof the metamaterial unit cells 104 a of the metamaterial board 100 islocalized at the center of the metamaterial board 100 using thecontactless capacitive coupling mechanism, however as shown in thefigure, the electric current spreads on all of the metamaterial unitcells 104 a of the metamaterial board 100 in order for radiation tooccur. In an alternate embodiment, the excitation of the metamaterialunit cells 104 a of the metamaterial board 100 may be localized at anylocation of the metamaterial board 100 using the contactless capacitivecoupling mechanism such that the electric current spreads on theplurality of the metamaterial unit cells 104 a of the metamaterial board100 in order for radiation to occur.

In an embodiment, in order for radiation to occur, the metamaterialboard 100 using the contactless capacitive coupling mechanism results inmore than one metamaterial unit cell 104 a being excited for radiationto happen. In such a case, the multiple metamaterial unit cells 104 a ofthe metamaterial board 100 has properties to work as a standard antenna.In an alternate embodiment, in order for radiation to occur, themetamaterial board 100 using the contactless capacitive couplingmechanism may have only a single metamaterial unit cell 104 a that maybe excited for radiation to happen. In such a case, the singlemetamaterial unit cell 104 a has properties to work as a standardantenna.

FIG. 1G illustrates a magnitude of electric current surface densitydistribution on a backing conductor layer 102 of a metamaterial board100 having a contactless capacitive coupling mechanism of FIG. 1A atoperation frequencies, according to an exemplary embodiment. As shown,the electric current concentrates at the center of the conductivebacking layer 102 of the metamaterial board 100, and thereby creating afocusing effect that directs the electromagnetic power radiated by themetamaterial unit cells 104 a of the metamaterial board 100 in an upwarddirection, that is, along the z-axis.

FIG. 2 illustrates an isometric view of a structure of a metamaterialboard 200 having a co-planar coupling mechanism, according to anexemplary embodiment. In this embodiment, the co-planar couplingmechanism is used to excite an array of metamaterial unit cells of themetamaterial board 200. The co-planar coupling mechanism is acontactless coupling mechanism, where a fewer number of metal layers maybe utilized, and thereby resulting in reduction of manufacturing cost.

The metamaterial board 200 illustrated may be realized in standardPrinted Circuit Board (PCB) technology utilizing two metal layers. Thetwo metal layers comprise a conductive backing layer 202 and ametamaterial layer 204. Also, a dielectric layer 206 is disposed betweenthe conductive backing layer 202, and the metamaterial layer 204. In themetamaterial board 200 fabrication, the conductive backing layer 202 isplaced at the bottom of the structure of the metamaterial board 200. Themetamaterial layer 204 may be deposited above the conductive backinglayer 202, and then may be etched to create an array of unit cells 204a. In an embodiment, a distance between the conductive backing layer 202and the metamaterial layer 204 is such that there is no short-circuitbetween the conductive backing layer 202 and the metamaterial layer 204in order to make the metamaterial unit cells 204 a radiate. Below themetamaterial layer 204 and above the conductive backing layer 202 may bedeposited a layer of dielectric 206 or insulating material, often asilicon dioxide.

The metamaterial layer 204 comprises the array of unit cells 204 a. Inthe illustrative figure, the metamaterial layer 204 of the metamaterialboard 100 comprises sixteen radiative metamaterial unit cells 204 a in afour-by-four (4×4) arrangement. Each of the metamaterial unit cell 204 amay include a surface. In one embodiment, the surface may be asubstantially flat surface. In another embodiment, the surface may notbe a flat surface or a substantially flat surface. The substantiallyflat surface of each of the array of unit cells 204 a may be a squaresurface containing a square metal patch 204 b with an aperture 204 cinscribed within it. The square metal patch 204 b does not completelyfill the unit cell surface, but is slightly smaller than the unit cell.The substantially flat surface of each of the array of unit cells 204 amay be a square metal patch 204 b with an aperture 204 c inscribedtherein. The aperture 204 c is defined such that a periphery of theaperture 204 c is within a periphery of the square metal patch 204 b bya spacing distance. In one example, the aperture 204 c may be a circularaperture. An element 204 d may be disposed within the aperture 204 c toform a circular slot. In the illustrated embodiment, since the aperture204 c is circular in shape, the element 204 d is a circular metal diskthat is disposed within aperture 204 c to form the circular slot. Itwill be appreciated by a person having ordinary skill in the art thatthe shape of the aperture 204 c is not limited to circular shape, andthe aperture 204 c may be of any other suitable shape without moving outfrom the scope of the disclosed embodiments. Also, the array composed ofmetamaterial unit cells 204 a contains square metal patches 204 b thatdo not touch each other, but are separated by narrow straight slots,since the unit cell surface is slightly larger than that of the squaremetal patches 204 b inscribed therein. In the illustrative figure, eachof the unit cells 204 a is attached to the neighboring unit cell 204 a,but the inscribed square metal patches 204 b corresponding to these unitcells are separated by small-sized slots. Further, there is a thin slotseparating the circular element 204 d from the periphery of the squaremetal patch 204 b. In an embodiment, one subset of the array of themetamaterial unit cells 204 a may be of one shape and size, and anothersubset of the array of the metamaterial unit cells 204 a may be ofanother shape and size.

The dielectric layer 206 is masked and etched to open narrow profileopenings known as vias 208. Each of the vias 208 respectively extends asan opening through the dielectric layer 206 to a portion of theuppermost layer. The vias 208 may be present to provide electrical pathsbetween different metal layers of the metamaterial board 200. In theillustrated figure, the vias 208 extend from the metamaterial layer 204to input RF ports 210. The input RF ports 210 may be located on orbehind the conductive backing layer 202. The geometries of the vias 208and the contact structures that now fill the vias 208 are usuallycircular although the vias 208 may also form other shapes such as atrench shape. The vias 208 have been positioned so that the metallicstructures that fill the vias 208 provide contacts between two separatedmetal layers of the metamaterial board 200. In order to form themetamaterial board 200 with the vias 208 as described above, once apattern of the vias 208 to traverse the layers is determined, theseparticular vias 208 may be machine drilled, punched, or etched throughthe layers. Alternative techniques for providing electrical pathsbetween the layers may be utilized.

In an embodiment, excitation components of the co-planar couplingmechanism may be placed on the plane of the metamaterial unit cells 204a of the metamaterial board 200 to excite the structure of themetamaterial board 200. In the present embodiment, the excitation of themetamaterial unit cells 204 a of the metamaterial layer 204 is achievedwithout direct contact by a capacitive structure which couples RF powerfrom the input RF port 210 to the metamaterial layer 204. The RF port210 is placed on the conductive backing layer 202, where the RF port 210feeding pads are placed within a small aperture in the conductivebacking layer 202. The co-planar coupling excitation mechanism utilizetwo metal layers of the metamaterial board 200.

In an embodiment, the two vias 208 connect to the RF port 210, andtherefore have a positive polarity and a negative polarity. One of thevias 208 at a negative potential is configured to excite half of themetamaterial unit cells 204 a and the other via of two vias 208 at apositive potential is configured to excite the remaining half of themetamaterial unit cells 204 a.

In illustrative embodiment, the metamaterial unit cell 204 a is a squaresurface surrounding the square metal 204 b comprising the aperture 204c, and the metallic element 204 d disposed within the aperture 204 c.The size of the aperture 204 c is inversely proportional to a frequencyof operation. If the size of the aperture 204 c is reduced, the size ofthe metallic element 204 d disposed within the aperture 204 c is alsoreduced, and then the frequency of the operation moves up. If the sizeof the aperture 204 c is increased, the size of the metallic element 204d disposed within the aperture 204 c also becomes larger, and thefrequency at which the metamaterial unit cell 204 a operates goes down.The aperture 204 c may be of circular shape. In an alternate embodiment,the aperture 204 c may be an elliptical shape. Alternate shapes may beutilized as well.

The radiating structure of the metamaterial board 200 is linearlypolarized, and has a transmit mode and a receive mode. In the transmitmode/configuration, the radiating structure of the metamaterial board200 emits radiation, where the electric field has a specific directionalong a single line. In the receive mode/configuration, the radiatingstructure of the metamaterial board 200 receives the radiation. In anembodiment, the radiation and impedance matching properties of themetamaterial board 200 having the co-planar coupling mechanism isidentical to the structure of the metamaterial board 100 of FIG. 1A.

FIG. 3A illustrates an isometric view of a structure of a metamaterialboard 300 having a direct feeding excitation mechanism, according to anexemplary embodiment. In this embodiment, the excitation mechanism usedis the direct feeding mechanism through conductive vias. The directfeeding excitation mechanism may utilize two metal layers, therebyresulting in reduction of manufacturing cost. In the direct feedingexcitation mechanism, the excitation of the metamaterial unit cells ofthe metamaterial board 300 does not happen with coupling eithercapacitively or coplanar, but happens when the vias directly connect tometamaterial unit cells.

The metamaterial board 300 illustrated here may be realized in standardPrinted Circuit Board (PCB) technology utilizing two metal layers. Thetwo metal layers may include a conductive backing layer 302, and ametamaterial layer 304. Also, a dielectric layer 306 may be disposedbetween the conductive backing layer 302, and the metamaterial layer304. In the metamaterial board 300 fabrication, the conductive backinglayer 302 is placed at the bottom of the structure of the metamaterialboard 300. The metamaterial layer 304 is deposited above the conductivebacking layer 302, and then may be etched to create an array of unitcells 304 a. In an embodiment, a distance between the conductive backinglayer 302 and the metamaterial layer 304 is such that there is noshort-circuit between the conductive backing layer 202 and themetamaterial layer 204 in order to make the metamaterial unit cells 304a radiate. Below the metamaterial layer 304 and above the conductivebacking layer 302 may be deposited a layer of dielectric 306 orinsulating material, often a silicon dioxide.

The metamaterial layer 304 comprises the array of unit cells 304 a. Inthe illustrative figure, the metamaterial layer 304 of the metamaterialboard 300 comprises sixteen radiative metamaterial unit cells 304 a in afour-by-four (4×4) arrangement. In the illustrative figure, each of theunit cells 304 a not attached to the other, and there is a small sizedslot separating these unit cells 304 a from each other. Each of themetamaterial unit cell 304 a may include a surface. In one embodiment,the surface may be a substantially flat surface. In another embodiment,the surface may not be a flat surface or a substantially flat surface.The substantially flat surface of each of the array of unit cells 304 amay be a square surface containing a square metal patch 304 b with anaperture 304 c inscribed within it. The square metal patch 304 b doesnot completely fill the unit cell surface, but is slightly smaller thanthe unit cell. The substantially flat surface of each of the array ofunit cells 304 a may be a square metal patch 304 b with an aperture 304c inscribed within it. The aperture 304 c is defined such that aperiphery of the aperture 304 c is within a periphery of the squaremetal patch 304 b by a spacing distance. In one example, the aperture304 c may be a circular aperture. An element 304 d may be disposedwithin the aperture 304 c to form a circular slot. In the illustratedembodiment, since the aperture 304 c is circular in shape, the element304 d is a circular metal disk that is disposed within aperture 304 c toform the circular slot. It will be appreciated by a person havingordinary skill in the art that the shape of the aperture 304 c is notlimited to circular shape, and the aperture 304 c may be of any othersuitable shape without moving out from the scope of the disclosedembodiments. Also, the array composed of metamaterial unit cells 304 acontains square metal patches 304 b that do not touch each other, butare separated by narrow straight slots, since the unit cell surface isslightly larger than that of the metal patch inscribed in it. In theillustrative figure, each of the unit cells 304 a is attached to theneighboring unit cell 304 a, but the inscribed square metal patches 304b corresponding to these unit cells 304 a are separated by small-sizedslots. Further, there is a thin slot separating the circular element 304d from the periphery of the square metal patch 304 b. In an embodiment,one subset of the array of the metamaterial unit cells 304 a may be ofone shape and size, and another subset of the array of the metamaterialunit cells 304 a may be of another shape and size.

The dielectric layer 306 may be masked and etched to open narrow profileopenings known as vias 308. Each of the vias 208 respectively extend asan opening through the dielectric layer 306 to a portion of theuppermost layer. The vias 308 may be present to provide electrical pathsbetween different metal layers of the metamaterial board 300. In theillustrated figure, the vias 308 extend from the metamaterial layer 304to input RF ports 310. The input RF ports 310 may be located on orbehind the conductive backing layer 302. The geometries of the vias 308and the contact structures which now fill the vias 308 are usuallycircular although the vias 308 may also form other shapes such as atrench shape. The vias 308 have been positioned so that the metallicstructures which fill the vias 308 provide contacts between twoseparated metal layers of the metamaterial board 300.

In an embodiment, excitation components of the direct feeding mechanismmay be placed on the plane of the metamaterial unit cells 304 a of themetamaterial board 300 to excite the metamaterial board 300. In thepresent embodiment, the excitation of the metamaterial unit cells 304 aof the metamaterial layer 304 is achieved by the vias 308. In anembodiment, the vias 308 may connect to the RF port 310 and thereforehave a positive polarity and a negative polarity. One of the vias 308 aat a negative potential is configured to excite half of the metamaterialunit cells 304 a and the other via of two vias 308 b at a positivepotential is configured to excite remaining half of the metamaterialunit cells 304 a.

In illustrative embodiment, the metamaterial unit cell 304 a may be asquare surface surrounding the square metal 304 b comprising theaperture 304 c, and the metallic element 304 d may be disposed withinthe aperture 304 c. The size of the aperture 304 c is inverselyproportional to a frequency of operation. If the size of the aperture304 c is reduced, the size of the metallic element 304 c disposed withinthe aperture 304 c is also reduced, and then the frequency of theoperation moves up. If the size of the aperture 304 c is increased, thesize of the metallic element 304 c disposed within the aperture 304 c isalso becomes larger, and then the frequency at which the metamaterialunit cell 304 a operates goes down. The aperture 304 c may be ofcircular shape. In an alternate embodiment, the aperture 304 c may be aneclipse shape. Alternate shapes may be utilized.

The radiating structure of the metamaterial board 300 is linearlypolarized, and has a transmit mode and a receive mode. In the transmitmode/configuration, the radiating structure of the metamaterial board300 emit radiation, where the electric field has a specific directionalong a single line. In the receive mode/configuration, the radiatingstructure of the metamaterial board 200 receives the radiations.

FIG. 3B illustrates a graph depicting a return loss of a metamaterialboard 300 having a direct feeding excitation mechanism of FIG. 3A,according to an exemplary embodiment. The return loss (reflected power)of the metamaterial board 300 having the direct feeding excitationmechanism is measured in dB. The metamaterial board 300 having thedirect feeding excitation mechanism resonates at a center frequency of5.9 GHz. The impedance matching here to a 50 Ohm RF port 310 is at −25dB. The impedance matching represents matching of the metamaterial board300 having the direct feeding excitation mechanism to a standard RF port310 which is typically 50 ohm. The impedance matching bandwidth at the−10 dB level is 350 MHz, or 6% with respect to a center frequency of themetamaterial board 300. The impedance matching defines the operationfrequency band of the metamaterial board 300 having the direct feedingexcitation mechanism.

FIG. 3C illustrates an isometric view of a radiation gain pattern of ametamaterial board 300 having a direct feeding excitation mechanism ofFIG. 3A, according to an exemplary embodiment. As shown, themetamaterial board 300 having the direct feeding excitation mechanismhas a single directive electromagnetic beam of energy that is radiatingupward/forward, that is, along the z-axis. The single directiveelectromagnetic beam is generated by excitation of entire sixteenmetamaterial unit cells 304 a of the metamaterial board 300.

FIG. 3D illustrates a magnitude of electric current surface densitydistribution on metamaterial cells layer 302 of a metamaterial board 300having a direct feeding excitation mechanism of FIG. 3A at operationfrequencies, according to an exemplary embodiment. The magnitude of theelectric current surface density distributed on the radiativemetamaterial unit cells 304 a of the metamaterial board 300 having thedirect feeding excitation mechanism, at the operating frequency band,where the metamaterial board radiates is shown. In one embodiment, aplurality of metamaterial unit cells 304 a of the metamaterial board 300are excited from the direct feeding excitation mechanism andsubsequently strong electric currents develop both on square patch edgesand on circular slot edges of each of the metamaterial unit cells 304 aof the metamaterial board 300. This results in the plurality ofmetamaterial unit cells 304 a of the metamaterial board 300 contributingto the electromagnetic radiation simultaneously, thereby leading to ahigh radiative gain of the metamaterial board 300. In anotherembodiment, all the metamaterial unit cells 304 a of the metamaterialboard 300 are excited from the direct feeding excitation mechanism dueto strong electric currents that develop both on the square patch edgesand on the circular slot edges of each of the metamaterial unit cells304 a of the metamaterial board 300. In this embodiment, all themetamaterial unit cells 304 a of the metamaterial board 300 contributingto the electromagnetic radiation simultaneously, thereby leading to ahigh radiative gain of the metamaterial board 300.

In an embodiment, although the excitation of the metamaterial unit cells304 a of the metamaterial board 300 is localized at the center of themetamaterial board 300 using the direct feed coupling mechanism, howeveras shown in the figure, the electric current spreads on all of themetamaterial unit cells 304 a of the metamaterial board 300 in order forradiation to occur. In an alternate embodiment, the excitation of themetamaterial unit cells 304 a of the metamaterial board 300 may belocalized at any location of the metamaterial board 300 such that theelectric current spreads on the plurality of the metamaterial unit cells304 a of the metamaterial board 300 in order for radiation to occur.

In an embodiment, in order for radiation to occur, the metamaterialboard 300 using the direct feed coupling mechanism may utilize more thanone metamaterial unit cell 304 a that causes excitation for radiation tohappen. In such a case, the multiple metamaterial unit cells 304 a ofthe metamaterial board 300 has properties to work as a standard antenna.In an alternate embodiment, in order for radiation to occur, themetamaterial board 300 using the direct feed coupling mechanism may havea single metamaterial unit cell 304 a that may be excited for radiationto happen. In such a case, the single metamaterial unit cell 304 a hasproperties to work as a standard antenna.

FIG. 3E illustrates an isometric view of a structure of a metamaterialboard 300 a having a direct feeding excitation mechanism, according toan exemplary embodiment. The structure of the metamaterial board 300 aof FIG. 3E is similar to the structure of the metamaterial board 300 ofFIG. 3A other than the dimensions and sizes of the metamaterial unitcells 304 a of the metamaterial board 300 a. The difference in thedimensions and sizes of the components such as metamaterial unit cells304 a of the metamaterial board 300 a in comparison to the dimensionsand sizes of the components such as metamaterial unit cells of themetamaterial board 300 aids to achieve the scaling of the operationfrequency. In this embodiment, circular slots on each of themetamaterial unit cells 304 a of the metamaterial board 300 a arenarrower than the circular slots on each of the metamaterial unit cellsof the metamaterial board 300 of FIG. 3A. Also, spacing distance betweenthe square patches of the metamaterial unit cells 304 a of themetamaterial board 300 a is narrower than the spacing distance betweenthe square patches of metamaterial unit cells of the metamaterial board300 of FIG. 3A. In the illustrated example, the circular slots on eachof the metamaterial unit cells 304 a of the metamaterial board 300 a are0.1 mm wide in comparison to the circular slots on each of themetamaterial unit cells of the metamaterial board 300 of FIG. 3A whichwere 0.15 mm wide. In the illustrated example, the total size of themetamaterial board in the embodiments described in FIG. 3A and FIG. 3Eis 20 mm×20 mm, however it is to be appreciated by a person havingordinary skill in the art that in other embodiments the size may varywithout moving out from the scope of the disclosed embodiments.

FIG. 3F illustrates a graph depicting a return loss of a metamaterialboard 300 a having a direct feeding excitation mechanism of FIG. 3E,according to an exemplary embodiment. The return loss (reflected power)of the metamaterial board 300 a having the direct feeding excitationmechanism is measured in dB. The metamaterial board 300 a having thedirect feeding excitation mechanism resonates at a center frequency of5.8 GHz. The center frequency is reduced by 150-100 MHz relative to theembodiments discussed in FIG. 3A without increase in the size of theoverall structure of the metamaterial board 300 a. The impedancematching to a 50-Ohm RF port is at −28 dB. The impedance matchingrepresents matching of the metamaterial board 300 a having the directfeeding excitation mechanism to a standard RF port which is typically 50ohm. The impedance matching bandwidth at the −10 dB level is 350 MHz, or6% with respect to a center frequency of the metamaterial board 300 a.

FIG. 4 illustrates an enlarged sectional view of a structure of ametamaterial board having a contactless capacitive coupling, a co-planarcoupling mechanism, and a direct feeding excitation mechanism, accordingto an exemplary embodiment. The metamaterial board 100 having thecontactless capacitive coupling mechanism, the metamaterial board 200having the co-planar coupling mechanism, and the metamaterial board 300having the direct feeding excitation mechanism have the same orsubstantially the same physical characteristics, operation bandwidth andperformance. In another embodiment, other excitation mechanisms toexcite the metamaterial board for radiation to happen may be used. Inyet another embodiment, hybrid combinations of the metamaterial board100 having the contactless capacitive coupling mechanism, themetamaterial board 200 having the co-planar coupling mechanism, and themetamaterial board 300 having the direct feeding excitation mechanismmay be employed.

In an embodiment, the metamaterial board 100 having the contactlesscapacitive coupling mechanism uses three metal layers. The metamaterialboard 200 having the co-planar coupling mechanism, and the metamaterialboard 300 having the direct feeding excitation mechanism uses two metallayers. The metamaterial board 100 having the contactless capacitivecoupling mechanism uses an extra metallic layer in comparison to themetamaterial board 200 having the co-planar coupling mechanism, and themetamaterial board 300 having the direct feeding excitation mechanism.Each layer of metal increases the cost of manufacturing and thereforethe manufacturing cost of the metamaterial board 200 having theco-planar coupling mechanism, and the metamaterial board 300 having thedirect feeding excitation mechanism is less than the metamaterial board100 having the contactless capacitive coupling mechanism. As themetamaterial board 300 having the direct feeding excitation mechanismuses two metal layers, the control of manufacturing process is morerobust in the metamaterial board 300 having the direct feedingexcitation mechanism by directly having the vias positioned on theactual metamaterial unit cells without having any circular patches witha specific slot exciting the central metamaterial unit cells of themetamaterial board 300.

In an embodiment, the size of the metamaterial unit cell in themetamaterial board 100 having the contactless capacitive couplingmechanism, the metamaterial board 200 having the co-planar couplingmechanism, and the metamaterial board 300 having the direct feedingexcitation mechanism is selected based on a desired operating frequency.The size of the metamaterial unit cell along with its adjacentmetamaterial unit cells determines the frequency of operation of themetamaterial board 100 having the contactless capacitive couplingmechanism, the metamaterial board 200 having the co-planar couplingmechanism, and the metamaterial board 300 having the direct feedingexcitation mechanism. The frequency of the unit cell is configured tooperate in a frequency band ranging from 900 MHz to 100 GHz. In anembodiment, the shape of the metamaterial unit cell in the metamaterialboard 100 having the contactless capacitive coupling mechanism, themetamaterial board 200 having the co-planar coupling mechanism, and themetamaterial board 300 having the direct feeding excitation mechanismsuch as thin slots are important for frequency tuning. In an embodiment,the diameter of each of the metamaterial unit cell of the metamaterialboard 100 having the contactless capacitive coupling mechanism, themetamaterial board 200 having the co-planar coupling mechanism, and themetamaterial board 300 having the direct feeding excitation mechanism isabout one-tenth of the wavelength of the frequency of operation.

FIG. 5A illustrates an isometric view of a structure of a metamaterialboard 500 having a direct feeding excitation mechanism, according to anexemplary embodiment. As previously described, number of metamaterialunit cells affects the performance of metamaterial board. In theillustrative embodiment, the size of the metamaterial board 500 isidentical or substantially identical to the size of the metamaterialboard 300 illustrated in FIG. 3A, but the metamaterial board 500 of theillustrative embodiment comprises four metamaterial unit cells 502 incomparison to the sixteen unit cells 304 a of the metamaterial board 300illustrated in FIG. 3A. In this embodiment, the excitation mechanismused is direct feeding excitation mechanism through conductive vias. Thedirect feeding excitation mechanism utilizes two metal layers, andthereby resulting in reduction of manufacturing cost. In the directfeeding excitation mechanism, the excitation of the metamaterial unitcells 502 of the metamaterial board 500 does not happen with couplingeither capacitively or coplanar, but happens when vias 504 directlyconnect to metamaterial unit cells 502. The direct feeding excitationmechanism is explained in detail in FIG. 3A.

FIG. 5B illustrates a graph depicting a return loss of a metamaterialboard 500 having a direct feeding excitation mechanism FIG. 5A,according to an exemplary embodiment. The return loss (reflected power)of the metamaterial board 500 having the direct feeding excitationmechanism is measured in dB. The metamaterial board 500 having thedirect feeding excitation mechanism resonates at a center frequency of5.8 GHz. This illustrates that the resonant frequency of operation isdetermined by design of the metamaterial unit cells 502 and is notdependent on the number of the metamaterial unit cells 502. Theimpedance matching to a 50-Ohm RF port is at or below −30 dB, which issmaller than the embodiments discussed earlier having sixteenmetamaterial unit cells. The impedance matching represents matching ofthe metamaterial board 500 to a standard RF port, which is typically 50ohm. The impedance matching bandwidth at the −10 dB level is 240 MHz, or4% with respect to a center frequency of the metamaterial board 500. Theimpedance matching defines the operation frequency band of the structureof the metamaterial board 500.

FIG. 5C illustrates a 3-dimensional isometric view of a radiation gainpattern of a metamaterial board 500 having a direct feeding excitationmechanism of FIG. 5A, according to an exemplary embodiment. As shown,the metamaterial board 500 having the direct feeding excitationmechanism has a single directive electromagnetic beam of energy that isradiating upward/forward. The single directive electromagnetic beam isgenerated by excitation of entire four metamaterial unit cells 502 ofthe metamaterial board 500. In the illustrative embodiment, the maximumgain is 5 dBi, which is 1 dB lower than the earlier embodimentsdiscussed comprising sixteen metamaterial unit cells. Since the size ofthe conductive backing layer is same in earlier and the presentembodiment, the directive radiation is caused by the collectiveexcitation of a plurality of metamaterial unit cells 502 in the presentembodiment as well as earlier embodiments.

FIG. 5D illustrates an isometric view of a structure of a metamaterialboard 500 a having a direct feeding excitation mechanism, according toan exemplary embodiment. The illustrative embodiment has themetamaterial board 500 a that may be identically configured to themetamaterial board 500 described in FIG. 5A, but not identical in allfacets and thus this results in a compact form factor in this structure.

FIG. 5E illustrates a graph depicting a return loss of a metamaterialboard 500 a having a direct feeding excitation mechanism FIG. 5D,according to an exemplary embodiment. The return loss (reflected power)of the metamaterial board 500 a having the direct feeding excitationmechanism is measured in dB. The metamaterial board 500 a resonates at acenter frequency of 5.75 GHz. The impedance matching to a 50 Ohm RF portis at or below −25 dB. The impedance matching represents matching of themetamaterial board 500 a to a standard RF port, which is typically 50ohm. The impedance matching bandwidth at the −10 dB level is 160 MHz, or3% with respect to a center frequency of the metamaterial board 500 a.The impedance matching defines the operation frequency band of thestructure of the metamaterial board 500 a.

FIG. 5F illustrates an isometric view of a radiation gain pattern of ametamaterial board 500 a having a direct feeding excitation mechanism ofFIG. 5D, according to an exemplary embodiment. As shown, themetamaterial board 500 a has a single directive electromagnetic beam ofenergy that is radiating upward/forward. The single directiveelectromagnetic beam is generated by excitation of entire fourmetamaterial unit cells 502. In the illustrative embodiment, the maximumgain is 4.4 dBi, which 0.6 dB lower relative to earlier embodimentdescribed with respect to FIG. 5A and 1.6 dB lower than the earlierembodiments comprising sixteen metamaterial unit cells. Since the sizeof a conductive backing layer is same in earlier and the presentembodiments, the directive radiation is caused by the collectiveexcitation of all metamaterial unit cells 502 in the present embodimentas well as earlier embodiments.

FIG. 6A illustrates a configuration of metamaterial unit cells for useas wearable antennas, according to an exemplary embodiment, and FIG. 6Billustrates an enlarged sectional view of the structure depicted in FIG.6A. The metamaterial unit cells 602 are of small size and the size ofthe metamaterial unit cells 602 is smaller than a radius of curvature ofa curved surface of any wrist wearable bracelet. This flexibility insize allows the metamaterial unit cells 602 to be etched on the curvedsurface of the bracelet. In the illustrated example, there is a wearablebracelet 604. The wearable bracelet 604 is made of a flexible plasticand is a flexible isolator. In one example, the thickness of the plasticis about 1.5 millimeters, and the inner diameter is about 60millimeters. The number of the metamaterial unit cells 602 is four, andthe metamaterial unit cells 602 are arranged in a linear arrayconfiguration. In the illustrated example, the size of each of the fourmetamaterial unit cells 602 is about six millimeters, however, it is tobe noted that in other embodiments the metamaterial unit cells 602 canbe of different size without moving out from the scope of the disclosedembodiments.

In the illustrated embodiment, the excitation mechanism employed forexciting the metamaterial unit cells 602 is a direct feeding excitingmechanism. It is to be noted that in other embodiments of the presentdisclosure, any other exciting mechanism may be employed for excitingthe metamaterial unit cells 602 without moving out from the scope of thedisclosed embodiments. In the direct feed exciting mechanism, a set ofvias may directly excite the metamaterial unit cells 602. In theillustrative embodiment, there is only a single row of the metamaterialunit cells 602, and therefore a double set of vias may not be utilized,and a single set of vias may be utilized to excite the single row of themetamaterial unit cells 602. In the single set of vias, one via 606 a isconfigured to have a positive polarity contact and another via 606 b isconfigured to have a negative polarity contact. The positive polarityvia 606 a feeds and/or excite half proportion of the row of themetamaterial unit cells 602, and the negative polarity via 606 b feedsand/or excite the other half proportion of the row of the metamaterialunit cells 602. The direct feed exciting mechanism is explained indetail in FIG. 3A.

In the illustrated example, the size of the each of the metamaterialunit cells 602 is 6 mm×6 mm×1.5 mm (bracelet thickness) or0.11×0.11×0.03 λ³, where λ is the wavelength at a frequency ofoperation. An inner diameter of the bracelet 604 is 60 mm which issimilar to that of a standard-size wrist-worn bracelet. Alternatedimensions of the bracelet 604 may be utilized for different purpose.

FIG. 6C illustrates a graph depicting a return loss of metamaterial unitcells as wearable antennas of FIG. 6A, according to an exemplaryembodiment. The return loss (reflected power) of the metamaterial unitcells 602 as wearable antennas is measured in dB. The metamaterial unitcells 602 as wearable antennas resonates at a center frequency of 5.75GHz where the reflection is at the minimum. The resonant frequency ofoperation is determined by design of the metamaterial unit cells 602 andis not dependent on the number of the metamaterial unit cells 602. Theimpedance matching is to a 50-Ohm RF port and is at or below −10 dB. Theimpedance matching represents matching of the structure to a standard RFport, which is typically 50 ohms. The impedance matching bandwidth atthe −10 dB level is 500 MHz, which is quite large, and defines theoperation frequency band of the structure of the metamaterial unit cells602 configured as wearable antennas. In addition to the other advantagesdescribed above, the present embodiment is ideal for wearable antennasdue to this large natural bandwidth because it is desirable to havespare bandwidth to accommodate impedance because the impedance providesa tuning effect from adjacent structures, such as from objects behindthe bracelet 604 (e.g., human hand).

FIG. 6D illustrates a 3-dimensional isometric view of a radiation gainpattern of metamaterial unit cells as wearable antennas of FIG. 6A,according to an exemplary embodiment. As shown, the metamaterial unitcells 602 as wearable antennas has a single directive electromagneticbeam of energy that is radiating upward/forward, that is, along thez-axis. The single directive electromagnetic beam is generated byexcitation of a plurality of the metamaterial unit cells 602 and thereis minimum radiation towards the inside of the bracelet 604 and into ahuman wrist. In the illustrative embodiment, a maximum gain is 3.7 dBi,and an antenna radiation efficiency is 91%.

FIG. 7A illustrates a structure of metamaterial unit cells configured aswearable antennas, according to an exemplary embodiment, and FIG. 7Billustrates an enlarged sectional view of the structure depicted in FIG.7A. FIG. 7A shows another embodiment of radiative metamaterials unitcells 702 as wearable/flexible/conformal antennas. In this embodiment, abracelet 704 may have the same dimensions as of the bracelet 604depicted in the embodiment of the FIG. 6A, however, there are threemetamaterials unit cells 702 of smaller size attached on a curvedsurface of the bracelet 704.

In the illustrative embodiment, the three metamaterials unit cells 702are probed with four RF ports 706, making the structure equivalent to anextremely dense 4-antenna array. In a receiving mode configuration, thethree metamaterials unit cells 702 absorbs RF energy which is directedto distinct prescribed locations. In other words, the threemetamaterials unit cells 702 operate as uniform materials that absorbelectromagnetic radiation with high absorption efficiency.

The three metamaterials unit cells 702 can be tapped by inserting fourlocalized RF ports 706 to the three metamaterials unit cells 702. Thispower is then directed specifically to the localized RF ports 706. Inview of that, this structure with the metamaterials unit cells 702 worksas a dense antenna array with many RF ports 706 that receive theabsorbed energy. Such structure is ideal for very physically smallreceivers where there is a need to distribute the received power tomultiple channels simultaneously. In addition, these multiple denselyplaced RF ports 706 can accept phase control, resulting inelectronically modulated RF patterns.

In an embodiment, this structure with the metamaterials unit cells 702has a very small form factor that matches a receiver ASIC (not shown).The ASIC is positioned in middle behind a conductive backing layerpositioned at the bottom of the structure, and would be configured toconnect its inputs to the four RF ports 706. Since the tapping can beperformed at different places, the ASIC may require less power per RFport. In order to obtain bandwidth in the structure, both the space aswell as thickness of a substrate is required. In the illustrativeembodiment, a 2 GHz bandwidth may be obtained using a structureincluding three metamaterial unit cells 702 and four RF ports 706.

FIG. 8A illustrates an isometric view of a structure of a metamaterialboard 800 configured as a flat antenna array that can be fabricated onstandard PCB boards, according to an exemplary embodiment. In anembodiment, radiative metamaterials unit cells 802 are configured as theantenna arrays to receive and/or transmit RF signals. The metamaterialsunit cells 802 are connected to 4 RF ports, making this structureequivalent of four antennas that are extremely closely spaced. Thepresent embodiment is the equivalent of the wearable configuration ofFIG. 7A, but on a flat platform appropriate for systems realized onstandard flat boards. In a receive mode of operation, the absorbed poweris then directed specifically to localized RF ports 804 and 806. Thestructure is ideal for physically small receivers where there is a needto distribute the received power to multiple channels simultaneously. Inaddition, the multiple densely placed RF ports 804 and 806 can acceptphase control, resulting in electronically modulated RF patterns.

In the illustrated example, the metamaterial unit cell 802 size is 6mm×6 mm×1.5 mm (bracelet thickness) or 0.11×0.11×0.03 λ³, where λ is thewavelength at the frequency of operation. The overall metamaterialstructure dimension is 6 mm×18 mm×1.5 mm or 0.11×0.33×0.03 λ³. Alternatedimensions of the metamaterial unit cell 802 and bracelet thickness maybe utilized.

FIG. 8B illustrates a graph depicting a return loss of a metamaterialboard 800 configured as an antenna array of FIG. 8A, according to anexemplary embodiment. The return loss (reflected power) of themetamaterial board 800 as the antenna array is measured in dB. Theimpedance matching is at −10 dB. The impedance matching representsmatching of the metamaterial board 800 as antenna array to a standard RFport, which is typically 50 ohm. The impedance matching bandwidth at the−10 dB level is 2 GHz, or 35% with respect to a center frequency of themetamaterial board 800. This defines the operation frequency band of themetamaterial board 800 as flat antenna array.

FIG. 8C illustrates an isometric view of a radiation gain pattern of ametamaterial board configured as an antenna array of FIG. 8A, accordingto an exemplary embodiment. As shown, the metamaterial board 800 as theantenna array has a single directive electromagnetic beam of energy thatis radiating upward/forward, that is, along the z-axis. The singledirective electromagnetic beam is generated by excitation of all of themetamaterials unit cells 802. In the illustrative embodiment, themaximum gain is 3.6-3.8 dBi. Since the size of a conductive backinglayer (positioned at the bottom of the metamaterial board 800) is sameas defined in earlier embodiments, a directive radiation is caused bythe collective excitation of a plurality of metamaterials unit cells 802in the present embodiment as well as earlier embodiments. Also, there isminimal radiation on the backside of the metamaterial board 800, and anantenna radiation efficiency is about 90%.

FIG. 9A illustrates an isometric view of a structure of a metamaterialboard including two orthogonal sub-arrays, according to an exemplaryembodiment. In the illustrated embodiment, there are two sub-arrays 902a and 902 b that are laid out on a common dielectric substrate. Each ofthe two sub-arrays 902 a and 902 b has three metamaterials unit cellsthat are connected to 4 RF ports, thereby making the structure of eachof the two sub-arrays 902 a and 902 b equivalent of four antennas thatare extremely closely spaced. The impedance matching of the twosub-arrays 902 a and 902 b, for all 8 RF ports, may be identical to eachmetamaterial board 800, shown in FIG. 8B.

In an embodiment, if only the metamaterials unit cells of the sub-array902 a of FIG. 9A are active, the 3D radiation gain as seen from the topis shown in FIG. 9B. The polarization, which is the electric fielddirection, of the structure, at a far-field point on the z-axis, is alsoshown in FIG. 9B. In an embodiment, if the metamaterials unit cells ofthe sub-array 902 b of FIG. 9A are active, the 3D radiation gain as seenfrom the top is shown in FIG. 9C. The polarization of the structure, ata far-field point on the z-axis, is also shown in FIG. 9C and thepolarization along the z-axis is orthogonal to the polarization of FIG.9C.

In the illustrative embodiment, when all eight RF ports of the structureare active, i.e., when both two sub-arrays 902 a and 902 b have activeRF ports, the radiation gain is shown in FIGS. 9D and 9E. The radiationgain has a rhombic, or rotated square shape. When the structure isimplemented as a receiver, per the radiation gain pattern shown, it isclear that the structure receives electromagnetic power polarized eitherin the x-axis or the y-axis direction, equally. Thus, this metamaterialboard structure with the two sub-arrays 902 a and 902 b is a verycompact and extremely efficient dual linear polarization receiver array.The structure may be able to receive both polarizations, and therefore asignal may always be present to charge a battery or other chargeabledevice from received RF signals.

FIG. 10 illustrates a method of forming a metamaterial board, accordingto an exemplary embodiment.

At step 1002, a backing layer is formed. In the metamaterial boardfabrication, the conductive backing layer is placed at the bottom of thestructure of the metamaterial board. At step 1004, a metamaterial layeris formed. The metamaterial layer may be formed by a metamaterialsubstrate. In one embodiment, the metamaterial layer may be depositedabove the conductive backing layer, and then may be etched to create anarray of metamaterial unit cells at step 1006. Hereinafter, the term“unit cell” and “metamaterial unit cell” may be interchangeably used. Inan embodiment, a distance between the conductive backing layer, and themetamaterial layer is such that there is no short-circuit between theconductive backing layer and the metamaterial layer in order to make themetamaterial unit cells radiate. Below the metamaterial layer and abovethe conductive backing layer 102 may be deposited a layer of dielectricor insulating material, often a silicon dioxide.

At step 1006, a plurality of partitions may be created. A surface iscreated in the metamaterial layer. In one embodiment, the surfacecreated is a substantially flat surface. In another embodiment, thesurface created is not a substantially flat surface or a flat surface.The surface of the metamaterial layer may be composed of a plurality ofpartitions The plurality of partitions are created on the surface of themetamaterial layer. Each of the plurality of partition includesidentical unit cells. In an alternative embodiment, two differentpartitions may contain different unit cells.

At step 1008, a unit cell is created in each partition. The unit cell isdefined as a surface, which by periodic repetition fills the surface ofeach partition. Within the surface of the unit cell, a metal patch of asquare or other arbitrary shape may be inscribed. Within the metal patchan aperture exists. The aperture is defined such that a periphery of theaperture is within a periphery of the metal patch by a spacing distance.At step 1010, a metallic element is disposed in each aperture to formunit cells. In one embodiment, the element is a circular element (ordisk) that may be disposed within each aperture to form unit cells. Theunit cell is therefore defined as the composite shape composed of theunit cell surface, the inscribed metal patch, the aperture within themetal patch and the metallic element within that aperture. Eachdifferent partition in the plurality of partitions that collectivelyforms the metamaterial layer, may be composed of different types of unitcells.

At step 1012, RF port is formed on backing layer. The RF ports may belocated on or behind the conductive backing layer. The RF ports mayinclude a housing having any arbitrary shape, and manufactured fromplastic, metal, or any other convenient material. At step 1014, unitcells are connected to RF port. The dielectric layer may be masked andetched to open narrow profile openings known as vias. The viasrespectively extend as an opening through the dielectric layer to aportion of the metamaterial layer. In one embodiment, the vias may bepresent to provide electrical paths between different metal layers ofthe metamaterial board by connecting the unit cells with the RF port.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the steps of the various embodiments must be performed inthe order presented. As will be appreciated by one of skill in the artthe steps in the foregoing embodiments may be performed in any order.Words such as “then,” “next,” etc. are not intended to limit the orderof the steps; these words are simply used to guide the reader throughthe description of the methods. Although process flow diagrams maydescribe the operations as a sequential process, many of the operationscan be performed in parallel or concurrently. In addition, the order ofthe operations may be re-arranged. A process may correspond to a method,a function, a procedure, a subroutine, a subprogram, etc. When a processcorresponds to a function, its termination may correspond to a return ofthe function to the calling function or the main function.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

Embodiments implemented in computer software may be implemented insoftware, firmware, middleware, microcode, hardware descriptionlanguages, or any combination thereof. A code segment ormachine-executable instructions may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. may be passed, forwarded, or transmitted via anysuitable means including memory sharing, message passing, token passing,network transmission, etc.

The actual software code or specialized control hardware used toimplement these systems and methods is not limiting of the invention.Thus, the operation and behavior of the systems and methods weredescribed without reference to the specific software code beingunderstood that software and control hardware can be designed toimplement the systems and methods based on the description herein.

When implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable orprocessor-readable storage medium. The steps of a method or algorithmdisclosed herein may be embodied in a processor-executable softwaremodule which may reside on a computer-readable or processor-readablestorage medium. A non-transitory computer-readable or processor-readablemedia includes both computer storage media and tangible storage mediathat facilitate transfer of a computer program from one place toanother. A non-transitory processor-readable storage media may be anyavailable media that may be accessed by a computer. By way of example,and not limitation, such non-transitory processor-readable media maycomprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othertangible storage medium that may be used to store desired program codein the form of instructions or data structures and that may be accessedby a computer or processor. Disk and disc, as used herein, includecompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk, and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions on a non-transitory processor-readable medium and/orcomputer-readable medium, which may be incorporated into a computerprogram product.

What is claimed is:
 1. A wireless transmission apparatus comprising: ametamaterial layer including a unit cell, wherein the unit cell includesa surface having a metal patch with an aperture, the aperture is definedsuch that a periphery of the aperture is within a periphery of the metalpatch by a spacing distance, and an antenna element is disposed withinthe aperture.
 2. The wireless transmission apparatus of claim 1, whereinthe metal patch is a square shaped substantially flat surface.
 3. Thewireless transmission apparatus of claim 1, wherein the antenna elementis a metallic element.
 4. The wireless transmission apparatus of claim1, wherein shape of the aperture is circular or elliptical.
 5. Thewireless transmission apparatus of claim 1, wherein the aperture is athrough-hole.
 6. The wireless transmission apparatus of claim 1, whereinthe unit cell is electromagnetically excited by a contactless capacitivecoupling.
 7. The wireless transmission apparatus of claim 1, wherein theunit cell is electromagnetically excited by a co-planar coupling.
 8. Thewireless transmission apparatus of claim 1, wherein the unit cell iselectromagnetically excited by a direct feeding mechanism using vias. 9.The wireless transmission apparatus of claim 1, wherein the unit cell isdesigned as a thin-sized reflector.
 10. The wireless transmissionapparatus of claim 1, wherein the unit cell is small in size, andwherein the small size unit cell is configured to be integrated oncurved shapes and geometries of wearable products.
 11. The wirelesstransmission apparatus of claim 1, wherein the unit cell in a receivingmode operates to absorb electromagnetic radiation with high absorptionefficiency.
 12. The wireless transmission apparatus of claim 1, whereinthe unit cell is configured to operate in a frequency band ranging from900 MHz to 100 GHz.
 13. The wireless transmission apparatus of claim 1,wherein the unit cell is configured to receive wireless signals.
 14. Amethod of forming a unit cell comprising: forming a metamaterial layerusing a metamaterial substrate; creating a surface on the metamateriallayer; creating a metal patch with an aperture in the surface of themetamaterial layer; and disposing an antenna element in the aperture toform the unit cell.
 15. The method of forming the unit cell of claim 14,further comprising forming the metamaterial substrate.
 16. The method offorming the unit cell of claim 14, wherein creating the surface includescreating a substantially flat surface.
 17. The method of forming theunit cell of claim 14, wherein creating the aperture includes creating acircular or elliptical aperture.
 18. The method of forming the unit cellof claim 14, wherein disposing the element includes disposing a metallicelement.
 19. The method of forming the unit cell of claim 14, whereinthe unit cell formed is configured to operate in a frequency bandranging from 900 MHz to 100 GHz.
 20. The method of forming the unit cellof claim 14, wherein the unit cell formed is configured to receivewireless signals.